The preposition de here means "from" in the sense of a change from one status to another,[2] not intending separation from the oppressed, but moving from a source in the oppressed.[3] Compare Ovid Fasti 5, 616: inque deum de bove versus erat, "he had been changed from an ox into a god", or Juvenal 7, 197: fies de rhetore consul, "from an orator you will become a consul". Oppresso is the past participle of opprimere ("to oppress") in the ablative case as governed by de, meaning "an oppressed person". The adjective Liber is in the nominative case, "a free person".

The motto resembles a quote from St. Augustine:[4]corripiendi sunt inquieti, [...] oppressi liberandi, "the turbulent have to be corrected, [...] the oppressed to be liberated". See also Isaiah 1:17: subvenite oppresso, "relieve the oppressed".